Top clips for anchoring window counterbalance springs on the spring covers of jamb liners have been troublesome. Sometimes during window assembly, the spring inside the spring cover is stretched and snapped loose, causing the spring to retract rapidly; and as a snapping spring goes coil-to-coil, the snap force is transmitted to the top of the spring. This can dislodge or break the anchorage that holds the upper end of the spring in place at the top of the spring cover. If the anchorage dislodges, the assembler must stop and waste time reinstalling the top clip on the spring cover; and if the anchorage or jamb liner breaks, the assembler must discard these parts and replace them with new parts, which can take even more time and expense. Either event adds to the cost of window assembly.
A U.S. Pat. No. 4,685,175, assigned to the assignee of this application, proposed a top clip that overlapped the top of the spring cover and anchored in place within the spring cover by a pair of wedged pins retained in holes in an upper region of the spring cover. Upward snapping spring force applied to this top clip can not only dislodge it from its anchored position, but can break the resin material of the jamb liner above the holes in which the top clip is anchored.
U.S. Pat. No. 4,190,930 suggests a top clip that hooks over and lodges in openings in an upper region of a jamb liner, but this top clip is used with a block and tackle balance system that is not subject to upward snapping force during assembly.
Other prior art top clips are formed by bending the uppermost coil of the spring into a hook that hooks over an upper edge of the spring cover. These can unseat the hook if the spring is snapped upward, and this requires repositioning the hook before proceeding with window assembly. Such hooks are also the weakest part of the spring and are likely to break during use.
These problems suggest a more firmly anchored top clip that cannot be dislodged during spring snapping force and is anchored in place securely enough so that no damage is done if the spring snaps. Work on such a concept has lead to a quite different solution, however. I have devised a top clip that is free to snap upward above the top of the spring cover, if the spring snaps, and that automatically reseats itself in an anchored position at the top of the spring cover, simply by pulling the spring and top clip back downward. A snapping spring then causes no damage to the top clip or the jamb liner and takes practically no time to restore, because the snapped spring merely has to be pulled back down. My anchoring system also accomplishes this with a simple and inexpensive top clip that functions reliably during the life of the window system.